#version 330 core

uniform vec2 u_resolution;

out vec4 FragColor;

float circleshape(vec2 position, float radius){
    return step(radius, length(position - vec2(0.5)));
}

void main()
{
    vec2 position = gl_FragCoord.xy / u_resolution;

    float circle = circleshape(position, 0.5);
    vec3 color = vec3(circle);

    FragColor = vec4(color, 1.0);
}
